Electronic devices, such as mobile telecommunication devices and Audio-Visual devices, have had various functions while having sizes, weights, and thicknesses reduced. A push switch used for operation panels in such devices is required to be thin and operate with a light click feeling, and may often include a sheet provided with a movable contact. The movable contact of the sheet is required to have a small size, to provide a light operation feeling, and to contact stably.
FIG. 4 is a plan view of conventional movable contact 1 disclosed in Japanese Patent Laid-Open Publication No. 2005-71783. FIG. 5 is a cross-sectional view of movable contact 1 at line 5-5 shown in FIG. 4. Movable contact 1 has a dome shape having its center swelling upward and has an oval shape seen from top provided by cutting both sides of a circular shape by parallel lines. Movable contact 1 is provided by punching and folding metal sheet, such as stainless steel sheet, having a spring property. A lot of movable contacts 1 may be arranged perpendicularly to the longitudinal direction of the oval shape.
An operation of movable contact 1 will be described below. Movable contact 1 is arranged to use with a fixed contact facing movable contact 1. A pushing force is applied to the swelling center of the dome shape. When the pushing force exceeds a predetermined level, the center of the dome shape turns swelling downward resiliently with a click feeling. This causes movable contact 1 to contact the fixed contact to be connected to the fixed contact electrically. Then, the pushing force applied to movable contact 1 is released or reduced. The pushing force is accordingly smaller than a predetermined level, movable contact 1 returns to its original dome shape resiliently by a self-restoring force with a click feeling. This allows movable contact 1 to remove from the fixed contact, hence being disconnected from the fixed contact electrically.
Movable contact 1 has the oval shape having both sides cut by straight lines. Movable contact 1, and consequently has a spring property smaller than that of a movable contact having a circular dome shape, accordingly providing a dull click feeling on a pushing operation. Further, movable contact 1 is required to contact a fixed contact stably.